Current sewerage treatments remove almost all toxic wastes such as "Drano", organophosphates, detergents, solvents, disinfectants, etc. Using reverse osmosis, all those things are removed from the water. There is 1 part of "non-H2O" for every 1 000 000 000 000 000 parts of H2O for water treated using reverse osmosis.
As for contaminated soils, I know of this place in Brisbane where there used to be a gas refinery or something and they want to build a motel, shopping complex and apartments on the land. The soil on the land is being removed to some facility out Ipswich way for treatment/disposal? I know that the whole process of removing the contaminated soil is a large undertaking because the whole area is sealed and covered to stop the dust spreading and something like 5-10m worth of soil has to be removed and replaced.